The present invention relates to dies for extruding flowable materials and more particularly dies for extruding two or more materials.
Coathanger dies for extruding flowable materials are well known in the art. For example, U.S. Pat. No. 5,175,925 issued Jan. 5, 1993 to Weber et al. teaches an extruding die having a static mixer insert. The static mixer takes the form of upstanding pins of various cross sections and arranged in substantially equally spaced sets. However, the Weber et al. die allows significant bypass flow on either side of the sets of pins. Further, Weber et al. does not allow for bilateral mixing which may be necessary for certain reactive components to achieve adequate blending and homogeneity.
U.S. Pat. No. 4,568,506 issued Feb. 4, 1986 to Kiriyama et al. teaches an extrusion die having a static mixer therein. Various commercially available static mixers are suggested. It is believed by the present applicants that each such static mixer has a round cross-section, except the Komax mixer which is said to have a square cross-section. Accordingly, the commercially available static mixers cannot fill the Kiriyama et al. coathanger die and therefore allow for bypass flow. Laminated plate type static mixers are also shown. However, Kiriyama et al. teaches fluids do not interact within the laminated plate type static mixer, and thus only allow for mixing at the discharging zone of the laminate plate type static mixer.
Further, the art does not teach a way to provide coathanger dies which deal with reactive materials having a particularly fast reaction time. If the reactive materials are introduced into the coathanger die and mixed, the residence time must be short enough to allow the final composition to be extruded to the desired shape prior to curing or other reactions occurring.
The invention comprises a die for extruding or otherwise providing flowable material therethrough in a longitudinal direction. The die has a die inlet for admitting the flowable material and a die outlet for extruding the flowable material. The die inlet and die outlet are oppositely disposed on a longitudinal axis. The die outlet has a cross sectional area defining a die outlet plane with a major axis and a minor axis. The die has a cavity connecting the die inlet and die outlet. The cavity has a plurality of cross sections perpendicular to the longitudinal direction. The cavity may have a static mixer filling the cavity at any cross section.
In another embodiment the invention comprises a die for extruding flowable material in a longitudinal direction. The die has a first die inlet and one or more auxiliary die inlets each for admitting flowable material into said die. The die further comprises a die outlet for extruding flowable material from said die. The first die inlet and auxiliary die inlets are spaced apart from each other. The first die inlet and/or auxiliary die inlet may also be used to admit energy into the die cavity. The energy may be used to cure/crosslink/disperse/blend one or more materials in the die cavity.